A known so-called dual fuel engine is capable of being driven while selecting one of a premixed combustion system in which fuel gas such as natural gas is mixed with air for combustion and a diffusion combustion system in which liquid fuel (fuel oil) such as heavy oil is diffused for combustion. Patent Literature 1 (PTL 1) discloses a dual fuel engine.
The dual fuel engine of PTL 1 includes a fuel injection valve that supplies fuel to combustion chambers during combustion in the diffusion combustion system and supplies fuel to the combustion chambers in order to ignite gaseous fuel during combustion in the premixed combustion system.